The present invention relates to a device and method for active cooling of a computer microprocessor (CPU) to speed up the processor, and to solve heat problems.
Processor power, and therefore speed, is increasing rapidly. From the beginning of personal computers and until now, the trend of CPU increasing temperature is clear.
The first processor models, such as XT, 286, 386 didn""t need any thermal solutions. Their power consumption and therefore temperature was low. When the 486 came out, it needed a small heat sink [aluminum plate attached to the CPU] to decrease and remove the heat. The heat is increased due to the number of transistors, also called CMOS devices, located on the silicone wafer, and increasing switching speed. Each CPU model had several versions of switching speed, and the switching speed and temperature are correlated.
The Pentium CPU needed a heat sink and a fan. Thus, a whole new market of passive cooling solutions emerged. Pentium II models came out with a different structure, with increasing power and heat. This CPU [and others such as the AMD Athlon CPU model] needed a very large heat sink and fan, and sometimes two fans or more. The trend of rising heat continued.
The heat of a CPU reduces its reliability, and therefore the reliability of the entire computer system, and affects the switching speed. Therefore, decreasing the CPU temperature will allow increasing of the switching speed. These phenomena are known as thermal acceleration.
The above described conventional cooling systems are all passive systems. This means that they remove heat from the CPU of the computer system, but do not actively input cold in order to actively cool the CPU and reduce the temperature of the CPU below ambient surrounding temperature. At present, passive cooling solutions are close to their limit. A new solution and approach are needed.
An attempt was made by Marlow Industries, Inc., Dallas, Tex., USA, to provide active cooling in its Model ST3404 PC chip cooler in May 1996. This simple device included a DT12-4 Thermoelectric cooler with a small heat sink, mounted adjacent a PC chip, and coupled to the motherboard. It provided heat dissipation up to 10 Watts and power input should not exceed 5 Volts DC, according to the manufacturer""s data sheet. The disadvantages of this device are that the total power of heat dissipation is very low, in terms of present day CPU requirements, and that is powered by the limited power of the power supply of the computer, so cannot receive sufficient power to dissipate more heat.
In addition, this TEC unit is inefficient, and therefore produces even more heat inside the computer enclosure, which heats other heat sensitive components, such as the hard drive, memory, chip set, etc.
Furthermore, when the computer is turned off or in the case of a power cut, a fast changing temperature vs. time often results in thermal shock, which could change characteristics of the CPU, reduce reliability. At the time, these were not a serious problems, as the change in temperature as a result of cooling was not very large, the thickness of the CPU silicon wafer was relatively large, and many fewer transistors were used than are in use at present and/or are expected to be used in CPU""s in the future. Another problem which arises when switching the unit off, is that the fast rise in temperature can cause water condensation in the unit""s cold side, which can lead to serious problems. Yet another problem is that the heat built up on the hot side of the thermoelectric module must be removed from the PC box. [While applying cooling to the CPU, the hot side of the thermoelectric-component is much hotter because of its low efficiency, around 30 percent]. Because of these disadvantages, and due to the changes in CPU power requirements, which could not be satisfied by this unit, this model ceased to be marketed some two years ago, as larger passive cooling systems were more efficient than this small active cooling system.
Another computer including an internal cooling system has been proposed by KryoTech, Inc., of West Colombia, S.C., USA. This computer utilizes a vapor phase cooling method, and includes a compressor and condenser with gas and moving mechanical parts mounted inside the computer. This cooling system increases the overall size of the computer by some 30-40%. Kryotec markets an accelerated speed computer, not a generic solution. Also Kryotech requires a special turn-off procedure to avoid thermal shock and condensation. This procedure must be followed by a human user, which can lead to mistakes and damage.
The present invention described below is a complete system that solves all the problems mentioned. In particular, it is a generic device, which can be mounted in any PC.
According to the present invention, there is provided an active cooling system for the CPU of a computer having computer slots and a motherboard, the cooling system including a card arranged to sit in a computer slot coupled to the motherboard, the card including a hot air outlet passage from inside the computer to outside the computer, a cooling-CPU unit including: a thermoelectric component (TEC) couplable via the card to the mains for power supply; a cold side heat sink coupled to the TEC by a aluminum or copper adapter/extender and in thermally conductive contact with a part of the CPU; a hot side heat sink coupled to the TEC; and a fan distanced from the hot side heat sink for pulling heated air from said hot side heat sink, and a flexible hose coupled between the fan and the hot air inlet passage on the card.